Tape reel



July 7, 1959 F. o. CARLSON 7 5 TAPE REEL Filed Jan. 24, 1955 2 Sheets-Sheet 1 INVENTOR Frederic/2 O. Caz-Z8021 July 1959 F. o. CARLSON v I 5 TAPE REEL Filed Jan. 24, 1955 2 Sheets-Sheet 2 Illllllllllm IIIIIIIIIII- 4' ll II IIII "1/ INVENTOR Frederw/o 0. Carbon ATT RN specific maximum value.

United States Patent TAPE REEL Frederick 0. Carlson, Monrovia, Calif., assignor, by mesne assignments, to H. K. Porter Company, Inc., of Pittsburgh, Pittsburgh, Pa., a corporation of Pennsylvama Application January 24, 1955, Serial No. 483,498

6 Claims. (Cl. 242-84.8)

This invention relates to measuring rulers employing a blade or tape coiled in a case and to be Withdrawn therefrom for use. This invention particularly pertains to such rulers employing a transversely bent, concavoconvex blade.

Rulers using a concavo-convex blade, commonly formed of steel, have been sold commercially for many years, and have had a significant advantage over other types of rulers in that the blade is highly rigid so that it may be held in extended position without support. This characteristic has made it possible for such a ruler to be operated by only one man. Predominantly, these rulers have been of the so-called push-pull type, generally including a coiled wind-up spring in the interior of the case to assist the operator in pushing the blade in. The resilience of the blade and the resilience of the spring are so correlated that the blade may be moved manually into and out of the casing with ease, and yet the blade is maintained substantially in any extended position to which it is set.

Early rulers of this general type used a blade approximately six feet in length, and, when carpenters and other users demanded a longer blade, this length was increased to about ten feet. Such ten-foot rulers have been well received in the trade, and their sales represent a substantial portion of the present market. However, the ten foot blade length has been found to be inadequate for many practical uses, such as vertical scaling to the second floor of a house, and consequently there has been considerable demand for longer blades which may be coiled up in a small case. Although the need for such a long-bladed ruler has been long recognized, no practical ruler construction employing a concavo-convex blade has yet been advanced to fill this need.

In general, if the ruler blade is to be lengthened, the wind-up spring of the push-pull type of ruler must correspondingly be lengthened; otherwise, the spring will be unable to provide the necessary tension throughout the entire range of blade movement into and out of the case. Thus, for a longer blade, the spring required for eifective operation will occupy a larger amount of space within the coils of the blade, and the blade coil must be arranged so that its inner diameter is sufiiciently large to permit the installation of such a spring.

When a concavo-convex blade is coiled, the longitudinal flexing of the blade produces a transverse flexure tending to straighten the cross-sectional arch into a fiat ribbon-like condition. However, to achieve this flat condition, which is necessary for proper winding and unwinding, a blade with a given radius of concavity must be flexed into a coil having a radius no larger than a.

Saidin another way, a concavo-convex blade has a natural radius of longitudinal flexure which is a function of its transverse radius of concavity; when the radius of concavity is increased, the natural radius of flexure is correspondingly increased, and vice versa. If one were to attempt to coil a concavoconvex blade into a circular form having a radius much 2,893,655. Patented July 7, 1959 larger than the natural radius of flexure of the blade, it would tend to deform out of the desired circular shape (wherein the blade is transversely flat) and would try to assume a shape having alternate straight and curved portions (e.g. somewhat in the form of a triangle with curved corners). Such deformation makes it difficult to move the blade into or out of a case, and may result in the blade making undesired frictional contact with the interior portions of the case.

To obtain the necessary rigidity for a relatively long blade, the radius of concavity must be relatively small, e.g. Experience has shown that when a blade greater than about 12 feet in length, and having the requisite rigidity, is used with a wind-up spring of proper capacity in a push-pull type of ruler, the inner diameter of the blade coil is too great to permit the blade to form into circular shape and lie flat. That is, the spring occupies so much space that the blade coil radius is too much greater than its natural radius of flexure, as determined by the required radius of concavity to give adequate rigidity, to allow the blade to coil into the ribbon-like condition necessary for proper winding and unwinding. Consequently, measuring rulers having rigid concave-com vex blades of a length greater than 12 feet, coilable in a compact casing, have not in the past been available to the tradesman.

It has been found, however, that highly rigid concavoconvex ruler blades of up to nearly 20 feet in length may be coiled flat within a compact ruler case of conventional size to be carried in one hand, in accordance with the construction to be described hereinbelow, and the ruler blade may be withdrawn freely and smoothly from the case without substantial friction between adjacent coils of the ruler or between the blade and the interior portions of the case.

Another problem with concavo-convex ruler blades results from their inherent tendency to resist bending. When coiled in flat condition, the blade tries to assume its original arched form, and produces a force reacting to unwind the coil. Thus, there is a natural tendency for such a blade to cause a reverse rotation Within the case, and this backlash effect makes it difficult to set and maintain a partially coiled concave-convex blade in a particular desired position. In accordance with another aspect of the present invention, this problem is solved by a winding mechanism having an efiicient anti backlash structure; and all of these operating elements are housed in the case in such a way that the ruler may easily be disassembled for cleaning or replacement of parts.

The invention accordingly consists in the features of construction, combinations of elements and arrangements as will be exemplified in the structure to be herein described and the scope of the application which will be set forth in the accompanying claims.

In the accompanying drawings a preferred embodiment of the invention is illustrated in which:

Figure l is a front elevation view of a ruler in accordance with the present invention, showing the hand crank mechanism in its closed position;

Figure 2 is a rear elevation view of the ruler;

Figure 3 is a perspective view of the interior of the ruler with the blade removed, showing the winding and anti-backlash mechanism;

Figure 4 is a slightly enlarged horizontal section through the ruler case taken along line 4-4 of Figure 2;

Figure 5 is a vertical section through the ruler case taken along line 5-5 of Figure 4, particularly showing the coiled ruler blade;

Figure 6 is a detailed section taken along line 6-6 of Figure 5, particularly showing the handle pivot structure; and 1 Figure 7 a perspective view showing the manner in'which the blade is coupled to the winding mechanism.

Referring now to Figures l through 3, the ruler includes a compact, D-shaped case consisting of mating shells ljlz fand 10b, which may'for example be'a zinc casting, andj'a concavo-couvex, steel blade 12,-s hown partly withdrawn from the case. Abuttin'g one side of-the case 10 and mounted for rotary motion with respect thereto, is acircular'face plate 1'4 (see Figure l) to which is Socureda crank '1 6'pivoted about itsleft hand end for swinging movement away from the" plane of the drawin'g. 'When swung 180 degrees to-itsopen position (see Figure 4), the crank 16, may be manually rotated by means of a handle "18 to turn the faceplate 14 and wind the bladef' 12 into thecase inamanner'to lie-explained in lersf a Referring now to Figure '5, the blade 12 passes into thefcasejltlthrough an'inclin ed passageway, generally diatedat 22, and is circularly coiled in flat condition he interior of the case. The inner end of the ruler blade'is secured to a rapid-disconnect strip 24, in a mannerishown in Figure 7,'to*permit the blade to be'fully withdrawn and readily disengaged forreplacement purposes. The outer end'of' the strip 24 extends through a transverse slot in the inner end of the blade and is tightly folded'back as shown at24a to assure a positive engagement between the two when the blade is coiled in the case. Referring again to Figure 5, the inner end of this strip '24 is curled back onto itself and riveted at 26 to form a loop which is fitted loosely over a central post 128 integral withand extendingperpendicularly away the face plate 14.

The strip 24 extends'radiallyoutwards of the post 23 fand,with"the blade 12, is wrapped about a light-weight winding drum formed'by a shallow circular rim 30 having an outer diameter of 1%,", and including four upstanding rods 32 evenly spaced about the periphery of the -rim 30. Therim and'the rods are integral with the faceplate 14 (see also Figure 3), and extend through a circular'opening in the sidewallof thecase 10. As 'best "seen in Figure 4, this opening has a'diameter slightly smaller than that of theface plate, and the side wall of fthe'case adjacent the opening is raised slightly at 11 and fdrmed with a smooth outer finish to provide a suitable beann surface forrota'ry motion of the face plate. The -shallow rim 30, which engages only the edge portion of .jth'e blzide 1 2, servesto' assure that'the blade coils into {circularshape 'when wound into the case, and'the rods 32 serve to maintain this'shape throughout the width of the blade.

"Inthe preferred embodiment described herein, the "blade 12 has a width of a radius of concavity of about /4 and an overall length of about 16 feet (i.e. 1:6 to 18 feet.) Such a blade'ishighly rigid, and when supported at one end only may be held out horizontally :for approximately 7 feet without buckling; also, it may beheld vertically (e.g. for scaling to the second story of a house) for its full length. By operating the crank '16,'the blade may-easily andpositively be 'drawn into the case-10, and the entire length will coilin a ribbonlikehtate so that 'it may readily be withdrawn from the case by hand. A blade of this rigidity-and length cannot be handled by the usual push-pull type of'ruler construction, mentioned briefly above. "Ithas also been found that the particular configura- "tion'of the wind-up mechanism described provides opti- ,mum operating characteristics when used with such a "blade. If a larger length blade of corresponding rigidity, were to be used, e.g. greater than 20 feet, or if the rigidity of the 16 footblade were increased, the. outer turns of the completely wound coil within the case would have too great adiameter to lie flat; consequently,the .wind-up operation would-be jumpy and the blade would be diincult to withdraw. On the other hand, if the rigidity of the-blade were substantially. reduced (as by increasing itsradiusof concavity) in order to increase the length of blade which could satisfactorily be coiled fiat within the case, the unsupported hold-out length of the blade would correspondingly be reduced to a value 5 unsuited for commercial usage. (For example, if the rigidity is reduced sutficientlyto permit a foot blade to be wound onto the-drum, the hold-out length of the blade would be only about 5 feet). Again, if the diameter of-the-drum were reduced to permit a longer length blade of proper rigidity, or a more rigid blade ofthe same length, tobe coiled within the case, the user would be required to make an undue number ofrevolutionsiof the crank-to wind the blade in. In addition, constructing a ruler of this type with a smaller drum diameter would require a corresponding decrease in the turning radius of the crank, as will be apparent from the following description of further details of the ruler mechanisrn, and hencewould makeit more difiicult to wind'thefbladejin'because of the decreased mechanical advantage.

Referring-now to-Figure 4, therim is formed with a small groove 36 extending around its outer periphery. A split retaining ring :38 (see also Figure 3) is fitted intothi's groove 36 and arranged so that its outer edge 'slidably' engages the inner surface of the raised portion surrounding the circular opening in the side wall of the case 10. This retaining ring-38 is given a slight bow (i.e. the ring is bent about a diametrical axis) so thatit applies a small amount of pressure continuously and sYmmetricallybetween-the casing wall and the rim 30. The edgeofthe groove 36 in therim 30 thereby serves as a'flange to receive the pressure of" the bowed retainin'g rir g 38. Thus, the face plate 14 is maintained in positiveaxial alignment with. the case at'all positions of 'theface plate, and the moderate frictional engagement creates a holding force which efiectively'eliminates backlash due to the tendency of the blade to unwind from its coiled'condition within the caseand create. a reverse rota'ionof thedrum.

'An'additional advantage ofthis arrangement is that ther'etaining ring .38 is located in a region where there is very littleaccumulation of dirt. Further, during operation, the. retaining ring rotates with the winding drum, andprovdes' a selfcleanng acton whch assures contnued andpr'ovides a self-cleaning action which assures con 'tinped'smooth performance even under severe adverse environmental conditions. The resiliency of the ring compensates for-ordinary frictional wear, and thereby 'maintainsfthedesired tensioning for eliminating backlas'h elfects. For. these reasons, this anti-backlash mechanism is not subject towear in' the usual sense, and provides an'eifective holding force after years of normal usage.

Referring'now toFigure l, 5 and 6, the pivoted end of .'the' crank16 consists of a tubular-member 40 mounted adjacent a rectangular opening located close' to the pe- Jriphery of'the'face plate 14. This member 40 is formed "with .a bore-passing longitudinally therethrough. Positioned in this bore is a cylindrical shaft or pin 42, the endsof which exten'dbeyond-the tubular member and intothei interior spaces formed by two raised portions 44' and46fformed'in, the face plate 14 at opposite ends of'the rectangular opening. The interior surfaces of these -raised portions surround theshaft 42 and thus prevent this shaft and the-tubular member 40 from moving outwardly. awayi fromithefaceplate.

Motion ..of the tubular member 40 through the rectangular opening towards'the interior ofthecase is re strainedhy a.yoke-shaped,vbent leaf spring 48 (see also J-EigureiB.),tone .-flat surface of which bears against: the inwardlyfaoing side of the. tubular member. 'Iihis leaf f springe'isw riveted tolthesintecior surface 1 of the: face plate 14. fAdvantageously; as; shown Figurev 6, the tubular 75 sm'embermfl) is formed with longitudinally extending opposing flat surfaces 40a and 40b so'arranged that the crank 16 is held in either its fully opened or fully closed position by engagement between the leaf spring 48 and the corresponding one of these flat surfaces. The :slight detent action thus provided by these opposing cam-like surfaces prevents the crank 16 from swinging loosely about the shaft 42 while the ruler blade is being wound in, and similarly assures that the crank is maintained in its closed condition, for greater compactness, when the ruler is not in use.

The face plate 14 is formed with a slightly elliptical hole 50, one edge of which is immediately adjacent the inner side wall of the rim 30. This hole 50 is spaced with respect to the'crank pivot axis in such a manner that when the crank is swung to its closed position, the handle 18 will pass through the hole and come to rest in the interior of the case. It may be noted that if the diameter of the rim 30 were reduced, it would be necessary correspondingly to move the handle 18 closer to the pivot axis of the crank 16 to prevent interference when the crank is placed in its closed position. Consequently, the mechanical advantage of the crank 16 would be decreased, making it more difficult to wind the blade into the case.

As shown in Figure 3, the case comprises two registering shells 10a and 10b. The left hand shell 10a is provided with a hole 52 in each of its four corners, and the right hand shell 10b is provided in its corners with studs 54 which are arranged to fit into the corresponding holes 52 in the left hand shell. Each stud is cored, so that the two shells 10a and 10b may be held firmly together by thread-cutting screws inserted through the holes 52.

It will be apparent from the above description that the bowed retaining ring 38 not only serves to eliminate backlash, but also serves to support all of the moving parts of the wind-up and anti-backlash mechanisms from only one of the shells 10a. With these moving parts thus completely assembled to one shell and positively held in alignment with respect thereto, there is no need to provide separate support means in the opposite shell 10b. Further, another special advantage of this arrangement is that the winding drum action is essentially independent of case distortions or damage resulting from abusive treatment given to the opposite shell 10b. In addition, the moving parts are readily accessible for repair or replacement without special tools, and if there is any damage to the shell 10a, it and the operating mechanism may easily be replaced as a unit.

It may also be noted that the D-shaped configuration of the case, with the blade withdrawable along a line parallel to the base of the case, makes it possible for one man to set the ruler down with the blade extended and walk back and forth along the full 16 foot length of the blade for layout work.

Referring now to Figure 4 as well as to Figure 3, the right shell 10b may be provided with a curved spring plate 56 so positioned that at certain points it applies pressure against the lower edge of the blade 12 when the blade is coiled in the case 10. This plate 56 prevents the blade from coiling in a helical pattern, and avoids jamming of the ruler due to such possible malfunctioning.

Although a specific preferred embodiment of the invention has been set forth in detail, it is desired to emphasize that this is not intended to be exhaustive or necessarily limitative; on the contrary, the showing herein is for the purpose of illustrating one form of the invention and thus to enable others skilled in the art to adapt the invention in such ways as to meet the requirements of particular applications, it being understood that various modifications may be made without departing from the scope of the invention as limited by the prior art.

1. In a measuring ruler, the combination comprising a compact casing adapted to be held in one hand and having an opening in one side thereof, a face plate mounted over said opening and bearing against theouter surface of said one side for rotary motion with respect to said casing, a drum mounted in said casing for carrying a coiled tapeblade, support means extending through said opening for securing said drum to said face plate for rotation therewith, said supportmeans being provided with a flange extending around the periphery thereof and in a plane parallel to the plane of said one side, and a retaining'ring' positioned between. said flange and the interior surface 'of said one casing side to se cure said drum to said casing, ,said retaining ring being shaped to applypressureitoboth said flange and said interior surface whereby to' produce a moderate amount of frictional resistance. to oppose the rotation of said drum.

2. In a measuring rulen'the combination comprising a compact casing adapted to beheld in one hand and having a circular opening in one side thereof, bearing means on the outer surface 'of'said 'one side and located adjacent the periphery of said opening, a face plate mounted in contact with said bearing means and arranged for rotary motion with respect to said casing, a drum mounted in said casing for carrying a coiled tape blade, circular support means extending coaxially through said opening and integrally securing said drum to said face plate for rotation therewith, said support means being provided with a flange extending around the periphery thereof to form a bearing surface facing the interior surface of said plate, a retaining ring mounted between said flange bearing surface and the interior surface of said one casing side to secure said drum to said casing, said retaining ring being shaped to apply pressure to both said flange and said casing side whereby to produce a moderate amount of frictional resistance to rotation of said drum, and manually-operable means secured to said face plate for imparting rotary motion to said drum.

3. In a measuring ruler, the combination comprising a compact casing adapted to be held in one hand and having a circular opening in one side thereof, a face plate mounted over said opening in contact with the outer surface of said one side and arranged for rotary motion with respect to said casing, a drum mounted in said casing with its axis perpendicular to the plane of said one casing side, a spring-metal tape blade coiled on said drum, said drum including a circular rim portion extending through said opening and integrally secured to said face plate so that said drum rotates with said face plate, said rim portion being provided with a groove extending around the periphery thereof, a retaining ring mounted in said groove and extending outside thereof to contact the interior surface of said one casing side to secure said drum to said casing, said retaining ring being shaped to apply pressure to both said rim and said casing side whereby to produce a moderate amount of frictional resistance to rotation of said drum, and a crank secured to said face plate to impart rotary motion to said drum.

4. In a measuring ruler, the combination comprising a compact casing adapted to be held in one hand and having a circular opening in one side thereof, a face plate mounted over said opening and bearing against the outer surface of said one side and arranged for rotary motion with respect to said casing, a drum mounted in said casing for carrying a coiled tape blade, support means extending through said opening for securing said drum to said face plate for rotation therewith, said support means being provided with a flange extending around the periphery thereof, and a split retaining ring mounted between said flange and the interior surface of said one casing side to removably secure said drum to said casing, said retaining ring being shaped to apply pressure to both meme 7 said: flange, and said ca ing; side whereby. toproduce' a'moderate amount of fijietionai resistance to rotation of said 5. The combination set forth in claim '4, wherein said i'ing 'is'bent about a diametrical aids thereof so as'to produce "avpressure contact with said flange and said '6. In ,a measuringuruler the combination comprising a compact casing a'daptedto be heidr inonehan'd and consisting of-,a pair1of matingshelis, one of said shells havingsa circulanopeninginfthe side thereof, a face plate .mountediovensaidopening in contaetj with the outer sur- Iface. of saidone shell and arranged for rotary motion respect..thereto, a drum. in said casiugffor carrying a (coiled tapeI blade, saidsdrumlincluding a circular rim extending through. saidopening andlintegrally secured to r'said face platessol that, said drum.-rotates with said face plate, said rim being provided with a groove extending aroundthe pe1iphery.,thereof,s.a split retaining ring mounted'in said; groove With;a.p0rti0n thereof .ex-

lending outside ofsaidgrooveto contact :the interior surface ofsaidoiteshellsidetoeecuresaid.drum to said casing-said retaining ring being' bent'about a diametxi axis thereof'to-applypressure to both-'said xim-aadd said casing sidewihereby'to'produce wmoderate amount of frictional "resistance to rotation of said *drum," and Crankmeans securdrto the outer surface of saidface plate to rotary motion thereto.

References Cited in the file ofthis patent UNITED STATES PATENTS 578,205 -Brownet a1. 'Mar.*2, 1897 1,058,311 Lewis etal, Apr. -8 1913 105,579 Putnam et a1. ;Tu1y'28, 1914 1,730,199 "Fan-and Oct. 1, 1929 1799;094 Farrand Mar. 31, 1931 1,939,546 'Farraud .Dec. .12, .1933 24001180. 'Fry May2'1,fl1935 2,066,405 f'Knowlton v 'Jan.'5 1937 "483,528 Christo'ii "Oct. "4, 1949 2,614,903 Stamper et a1 Oct. L21, 1952 2,'636;694 1953 Evans Apr. 28,, 

